(a) Technical Field
The present invention relates to a pedal force controlling apparatus for a brake pedal simulator, and more particularly to an apparatus that controls push force characteristics of a pedal in a brake system employing a pedal simulator.
(b) Background Art
In general, a brake-by-wire system for a vehicle refers to a system which does not include a mechanical connection between a driver and a brake wheel but allows electric calipers disposed within the wheels of the vehicle and controlled by a controller to hold disks disposed within the electric calipers of the wheels to brake the vehicle. Brake-by-wire systems include electromechanical brakes using power of an actuator having a 12 V motor as wheel disk braking power, and electro-wedge brakes having regenerative motor power with a wedge structure for wheel disk braking power to create high braking power.
A brake-by-wire system includes a mechanical apparatus that provides hydraulic pushing force characteristics to allow a driver to feel pressure during a manipulation of a pedal and an electric apparatus that recognizes a pedal intention of the driver, wherein a pedal simulator is used as the electric apparatus. The pedal simulator generally employs a pushing force by a rubber damper or a spring, a magnetic force by a magnet, and a viscosity change of an magentorheological (MR) fluid, and detects pedal force characteristics, for example, of hydraulic pressure while not employing hydraulic pressure, providing an adequate pedal force to the driver.
A known developed technology controls an initial mounting load of a stroke simulator spring with a motor and a controller to change pushing force characteristics of a pedal, and controls pushing force characteristics based on a travel condition of the vehicle with a travel state detection mechanism of the vehicle. Accordingly, the system includes a brake manipulating member; a controller that is configured to change the pushing force/stroke characteristics, detect an operation state/travel environment, and operate a pushing force/stroke based on a travel state of the vehicle.
However, the developed technology requires a motor, a gear, and a screw, and a separate mechanism that controls the motor as well, resulting in an increase in manufacturing costs, an increase in weight, and a complexity of the structure, and a difficulty in packaging.